Interannual Variability of Summer Surface Solar Radiation over China: Role of Mid–High-Latitude Atmospheric Circulation Anomalies

Abstract Surface solar radiation (SSR), a crucial renewable energy resource, plays a key role in achieving carbon peak and neutrality goals. This study investigates the interannual variability of summer SSR anomalies over China from 1980 to 2023, focusing on their dominant modes and underlying mechanisms. The empirical orthogonal function (EOF) analysis reveals two primary modes of SSR variability. The first, the Yangtze River valley (YRV) mode, explains 25.1% of the variance and shows coherent SSR variations along the YRV. Its positive phase is associated with a positive North Atlantic Oscillation, which triggers a Rossby wave train that propagates from Eurasia to East Asia. This wave train induces an anticyclonic anomaly over the Korean Peninsula and a cyclonic anomaly over southern China, leading to reduced cloud cover through moisture divergence and descending motion, thereby increasing SSR in the YRV. The second mode, a meridional dipole pattern, accounts for 14.9% of the variance and features out-of-phase SSR changes between northern/western and southern China. Its positive phase results from a quasi-barotropic Rossby wave train driven by intensified rainfall in northern Europe, which induces moisture flux convergence/divergence and vertical motion that modulate cloud cover, thus decreasing SSR in northern and western China while increasing it in southern China. These findings highlight the dominant role of mid–high-latitude atmospheric circulation anomalies in driving SSR variability through cloud modulation on interannual time scale, with El Niño–Southern Oscillation (ENSO) exerting a secondary influence. The results emphasize the greater impact of mid–high-latitude anomalies on East Asian SSR compared to ENSO, presenting challenges for forecasting due to the high internal variability of the midlatitude atmosphere. Significance Statement Surface solar radiation (SSR) is critical for renewable energy production and achieving carbon neutrality goals. While previous studies have emphasized the strong link between tropical El Niño–Southern Oscillation (ENSO) and summer climate anomalies in East Asia, our study reveals that mid–high-latitude atmospheric circulation anomalies are the dominant drivers of SSR interannual variability in China. Through the empirical orthogonal function analysis, we identify two key modes of SSR variability: the Yangtze River valley mode and a meridional dipole mode. Both are shaped primarily by atmospheric circulation patterns originating in mid–high latitudes through their regulation of cloud, with ENSO exerting a secondary influence. This underscores the complex interplay of tropical and extratropical factors in shaping summer SSR patterns. Moreover, the high internal variability of the midlatitude atmosphere poses challenges for accurate seasonal SSR forecasting. These findings shift focus from ENSO to high-latitude dynamics, offering new insights for improving climate prediction and renewable energy planning in East Asia.